Effects of Mulberry Leaf Flavonoids on Growth Performance, Intestinal Tissue Structure, Digestive Enzyme Activities, Nutrient Apparent Digestibility and Serum Biochemical Indexes of Meat Rabbits

YANG Mengqi; WANG Gan; WU Zhihong; ZHU Yujing; LI Fangfang

doi:10.12418/CJAN2024.567

2024 , Vol. 36 >Issue 10: 6665 - 6672

DOI: https://doi.org/10.12418/CJAN2024.567

RESEARCH PAPER

Effects of Mulberry Leaf Flavonoids on Growth Performance, Intestinal Tissue Structure, Digestive Enzyme Activities, Nutrient Apparent Digestibility and Serum Biochemical Indexes of Meat Rabbits

YANG Mengqi ,
WANG Gan ,
WU Zhihong ,
ZHU Yujing ,
LI Fangfang ^,^*

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College of Animal Science and Medicine, Shenyang Agricultural University, Shenyang 110866, China

^*associate professor, E-mail: lffsyau@syau.edu.cn

Received date: 2024-04-01

Online published: 2024-10-14

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Abstract

This experiment was conducted to study the effects of dietary difference supplemental levels of mulberry leaf flavonoids on growth performance, intestinal tissue structure, digestive enzyme activities, nutrient apparent digestibility and serum biochemical indexes of meat rabbits. The experiment adopted a single factor experimental design, one hundred and twenty 42-day-old Ira rabbits with good physical condition and similar body weight were selected and randomly divided into 4 groups with 5 replicates in each group and 6 rabbits in each replicate. Rabbits in the control group were fed a basal diet, and others in experimental groups were fed the basal diets supplemented with 30, 60 and 90 mg/kg mulberry leaf flavonoids, respectively. The pre-experimental period lasted for 7 days, and the experimental period lasted for 35 days. The results showed as follows:1) compared with control group and 30 and 60 mg/kg mulberry leaf flavonoids groups, the final body weight and average daily gain of 90 mg/kg mulberry leaf flavonoids group were significantly increased (P<0.05), and the feed to gain ratio was significantly decreased (P<0.05); compared with the control group, the mortality rate of 30, 60 and 90 mg/kg mulberry leaf flavonoids groups was significantly decreased (P<0.05). 2) Compared with the control group, the duodenal villus height and villus height/crypt depth of 30, 60 and 90 mg/kg mulberry leaf flavonoids groups were significantly increased (P<0.05); compared with control group and 30 and 60 mg/kg mulberry leaf flavonoids groups, the duodenal crypt depth of 90 mg/kg mulberry leaf flavonoids group was significantly decreased (P<0.05). 3) Compared with control group and 30 mg/kg mulberry leaf flavonoids group, the activities of amylase and lipase in jejunum of 60 and 90 mg/kg mulberry leaf flavonoids groups were significantly increased (P<0.05), and the activities of amylase and trypsin in ileum were significantly increased (P<0.05); compared with control group and 30 and 60 mg/kg mulberry leaf flavonoids groups, the ileal lipase activity of 90 mg/kg mulberry leaf flavonoids group was significantly increased (P<0.05). 4) Compared with control group and 30 and 60 mg/kg mulberry leaf flavonoids groups, the apparent digestibility of dry matter and crude fiber of 90 mg/kg mulberry leaf flavonoids group was significantly increased (P<0.05); compared with the control group, the apparent digestibility of gross energy, crude protein and ether extract of 30, 60 and 90 mg/kg mulberry leaf flavonoids groups was significantly increased (P<0.05); compared with control group and 30 mg/kg mulberry leaf flavonoids groups, the acid detergent fiber apparent digestibility of 60 and 90 mg/kg mulberry leaf flavonoids group was significantly increased (P<0.05). 5) compared with control group and 30 and 60 mg/kg mulberry leaf flavonoids groups, the contents of glucose and urea nitrogen in serum of 90 mg/kg mulberry leaf flavonoids group were significantly decreased (P<0.05). In conclusion, dietary mulberry leaf flavonoids can improve the intestinal digestive enzyme activities nutrient apparent digestibility and intestinal morphology of meat rabbits, then improve the growth performance. Under the conditions of this experiment, the dietary appropriate supplemental level of mulberry leaf flavonoids for meat rabbits is 90 mg/kg.

Key words： mulberry leaf flavonoids; meat rabbits; growth performance; nutrient apparent digestibility; serum biochemical indexes; intestinal tissue structure

Cite this article

YANG Mengqi , WANG Gan , WU Zhihong , ZHU Yujing , LI Fangfang . Effects of Mulberry Leaf Flavonoids on Growth Performance, Intestinal Tissue Structure, Digestive Enzyme Activities, Nutrient Apparent Digestibility and Serum Biochemical Indexes of Meat Rabbits[J]. Chinese Journal of Animal Nutrition, 2024 , 36(10) : 6665 -6672 . DOI: 10.12418/CJAN2024.567

桑叶黄酮(mulberry leaf flavonoids,MLF)是一种植物活性物质,可作为绿色饲料添加剂,具有天然无毒副作用、无残留等优点,目前成为养殖业的研究热点^[1]。将桑叶黄酮应用在畜禽饲料中可避免因滥用抗生素引起的耐药性等问题^[2]。李向荣等^[3]研究发现,桑叶黄酮可以加快动物体内胆固醇的转运速度和代谢效率,有降血脂的作用。Kong等^[4]研究发现,饲粮中添加桑叶黄酮可显著提高犊牛平均日增重(ADG),从而提高犊牛断奶后对饲料的利用率。Huang等^[5]研究表明,饲粮中添加桑叶黄酮可显著提高蛋鸡血清及壳腺中的钙含量和壳腺中的酶活性,说明桑叶黄酮可增强壳腺的抗氧化能力,提高蛋品质。王密^[6]研究发现,桑叶黄酮可改善肉鸡肉品质,降低肉鸡血脂水平。丰源等^[7]研究表明,饲粮中添加桑叶黄酮可以提高产蛋率。张波^[8]研究表明,饲粮中添加1.2%桑叶提取物可显著提高蛋壳强度,改善蛋黄颜色。桑叶黄酮具有提高动物机体抗氧化能力、抗菌、降血脂等作用,在猪、鸡生产方面有较多应用研究,但在肉兔生产中研究较少。因此,本试验旨在研究饲粮中添加不同水平桑叶黄酮对肉兔生长性能、肠道组织结构和消化酶活性、营养物质表观消化率及血清生化指标的影响,为改善肉兔生长性能提供理论依据。

1 材料与方法

1.1 试验材料

试验所用桑叶黄酮纯度为50%。

1.2 试验动物与试验设计

试验选取体重相近、体况良好的42日龄伊拉肉兔120只,随机分为4个组,每组5个重复,每个重复6只(公母各占1/2)。对照组饲喂基础饲粮,试验组分别在基础饲粮中添加30、60和90 mg/kg的桑叶黄酮。试验期42 d,其中预试期7 d,正试期35 d。所有涉及动物的程序都遵循沈阳农业大学动物福利委员会批准的伦理规范(批准文号:2022092801)。基础饲粮参照《肉兔营养需要量》(NY/T 4049—2021)^[9]配制,其组成及营养水平见表1。

表1 基础饲粮组成及营养水平(风干基础)

Table 1 Composition and nutrient levels of the basal diet (air-dry basis)%

原料 Ingredients	含量 Content	营养水平 Nutrient levels²⁾	含量 Content
玉米 Corn	24.00	消化能 DE/(MJ/kg)	10.12
小麦麸 Wheat bran	18.00	粗蛋白质 CP	15.77
干酒糟及其可溶物 DDGS	12.00	粗纤维 CF	16.49
花生秧 Peanut vine	13.30	中性洗涤纤维 NDF	32.34
花生壳 Peanut shell	20.00	酸性洗涤纤维 ADF	21.40
豆粕 Soybean meal	11.00	酸性洗涤木质素 ADL	6.39
骨粉 Bone meal	0.40	赖氨酸 Lys	0.76
预混料 Premix¹⁾	1.00	含硫氨基酸 Sulfur amino acids	0.60
食盐 NaCl	0.30	钙 Ca	0.61
合计 Total	100.00	总磷 TP	0.43

1)预混料为每千克饲粮提供 The premix provided the following per kg of the diet:Fe 70 mg,Cu 20 mg,Zn 70 mg,Mn 10 mg,Se 0.25 mg,I 0.2 mg,VA 10 000 IU,VD 900 IU,VE 50 mg,VK₂ mg,D-泛酸 D-pantothenic acid 50 mg,VB₁₂ 0.02 mg,烟酸 niacin acid 50 mg,赖氨酸 Lys 2 g,蛋氨酸 Met 1.5 g。

2)消化能、赖氨酸和含硫氨基酸为计算值^[9],其余为实测值。DE, Lys and sulfur amino acids were calculated values^[9], while the others were measured values.

1.3 饲养管理

采用常规饲养管理,常规免疫程序,各组饲养条件一致。试验兔自由采食和饮水,自然光照和通风。试验期间每天各组定量喂食并清扫兔舍。

1.3 测定指标与方法

1.3.1 生长性能

试验开始与结束当天,肉兔空腹以重复为单位进行称重,每天记录采食量,计算平均日采食量(ADFI)、平均日增重和料重比(F/G)。每日对兔群的腹泻和死亡情况进行记录,计算死亡率和腹泻频率,计算公式如下:

死亡率(%)=100×死亡兔只数/试验兔总数;

腹泻频率(%)=[试验期内腹泻只日数/(试验天数×试验只数)]×100^[10]。

1.3.2 十二指肠组织结构

试验结束当天,在十二指肠中段截取3 cm左右肠段,放入4%的多聚甲醛溶液中制备组织切片,观测绒毛高度(villus height,VH)和隐窝深度(crypt depth,CD),计算绒毛高度/隐窝深度(VH/CD)。

1.3.3 肠道消化酶活性

试验结束当天,采集十二指肠内容物放入冻存管,于-20 ℃冻存。采用南京建成生物工程研究所生产的试剂盒,结合MERASH UV 5000PC型紫外可见分光光度计(上海元析仪器有限公司),采用比色法测定肠道淀粉酶(AMY)、胰蛋白酶(TPS)和脂肪酶(LPS)活性。

1.3.4 营养物质表观消化率

试验结束前4 d,采用全收粪法收集粪便,喷加10%盐酸固氮,于-20 ℃冻存。饲粮和粪便中干物质(DM)、粗蛋白质(CP)、粗脂肪(EE)、粗纤维(CF)、钙(Ca)、总磷(TP)含量分别参照GB/T 6435—2014、GB/T 6432—2018、GB/T 6433—2006、GB/T 6434—2006、GB/T 6436—2018、GB/T 6437—2018的方法进行测定,酸性洗涤纤维、中性洗涤纤维和酸性洗涤木质素含量分别参照NY/T 1459—2022、GB/T 20806—2022、GB/T 20805—2006的方法进行测定,总能按照ISO 9831:1998采用氧弹式能量仪(IKA-C 200)进行测定。

1.3.5 血清生化指标

试验结束第2天,每重复选取1只试验兔进行采血,血液静置30 min,4 ℃、2 000×g离心15 min,分离血清,于-20 ℃冻存。采用南京建成生物工程研究所生产的试剂盒测定血清葡萄糖(GLU)、总蛋白(TP)、白蛋白(ALB)、尿素氮(UN)含量及碱性磷酸酶(ALP)活性。

1.4 数据分析

以组为单位统计死亡率,以重复为单位统计其余指标。采用SPSS 24.0软件ANOVA程序进行方差分析,采用Duncan氏法进行多重比较,腹泻频率、死亡率采用卡方检验。除腹泻频率和死亡率外,数据结果用“平均值±标准差”表示,P<0.05表示差异显著。

2 结果

2.1 桑叶黄酮对肉兔生长性能的影响

由表2可知,与对照组和30、60 mg/kg桑叶黄酮组相比,90 mg/kg桑叶黄酮组的终末体重和平均日增重显著提高(P<0.05),料重比显著降低(P<0.05);与对照组相比,30、60和90 mg/kg桑叶黄酮组的死亡率显著降低(P<0.05)。各组之间平均日采食量和腹泻频率无显著差异(P>0.05)。

表2 桑叶黄酮对肉兔生长性能的影响

Table 2 Effects of MLF on growth performance of meat rabbits

项目 Items	桑叶黄酮添加水平 MLF supplemental levels/(mg/kg)				P值 P-value
项目 Items	0 (对照 Control)	30	60	90	P值 P-value
初始体重 IBW/g	959.02±15.17	958.16±19.23	949.66±17.86	952.34±15.90	0.953
终末体重 FBW/g	1 886.04±68.23^b	1 904.74±245.06^b	1 926.03±66.27^b	2 045.17±96.05^a	0.003
平均日采食量 ADFI/g	105.86±3.86	104.44±1.75	106.16±3.02	106.41±3.07	0.738
平均日增重 ADG/g	26.49±4.22^b	27.05±3.71^b	27.90±3.71^b	31.22±2.45^a	0.020
料重比 F/G	3.99±0.67^a	3.86±0.42^a	3.81±0.59^a	3.40±0.24^b	0.023
腹泻频率 Diarrhea frequency/%	5.37	4.85	4.12	2.63	0.087
死亡率 Mortality rate/%	6.67^a	3.34^b	3.34^b	0^c	0.002

	同行数据肩标不同小写字母表示差异显著(P<0.05),相同或无字母表示差异不显著(P>0.05)。下表同。
	In the same row, values with different small letter superscripts mean significant difference (P<0.05), while with the same or no letter superscripts mean no significant difference (P>0.05). The same as below.

2.2 桑叶黄酮对肉兔十二指肠组织结构的影响

由表3可知,与对照组相比,30、60和90 mg/kg桑叶黄酮组的十二指肠绒毛高度和绒毛高度/隐窝深度显著提高(P<0.05);与对照组和30、60 mg/kg桑叶黄酮组相比,90 mg/kg桑叶黄酮组的十二指肠隐窝深度显著降低(P<0.05)。

表3 桑叶黄酮对肉兔十二指肠组织结构的影响

Table 3 Effects of MLF on duodenal tissue structure of meat rabbits

项目 Items	桑叶黄酮添加水平 MLF supplemental levels/(mg/kg)				P值 P-value
项目 Items	0 (对照 Control)	30	60	90	P值 P-value
绒毛高度 VH/μm	902.43±97.30^b	937.46±102.87^a	944.34±100.96^a	975.68±86.27^a	0.033
隐窝深度 CD/μm	126.35±16.38^a	121.15±37.67^a	119.86±29.28^a	108.34±45.39^b	0.038
绒毛高度/隐窝深度 VH/CD	7.14±2.93^b	7.74±2.55^a	7.88±2.88^a	9.01±2.75^a	0.046

2.3 桑叶黄酮对肉兔肠道消化酶活性的影响

由表4可知,与对照组和30 mg/kg桑叶黄酮组相比,60和90 mg/kg桑叶黄酮组的空肠淀粉酶、脂肪酶活性显著提高(P<0.05),回肠淀粉酶、胰蛋白酶活性显著提高(P<0.05);与对照组和30、60 mg/kg桑叶黄酮组相比,90 mg/kg桑叶黄酮组的回肠脂肪酶活性显著提高(P<0.05)。各组之间空肠胰蛋白酶活性无显著差异(P>0.05)。

表4 桑叶黄酮对肉兔肠道消化酶活性的影响

Table 4 Effects of MLF on intestinal digestive enzyme activities of meat rabbits

项目 Items	桑叶黄酮添加水平 MLF supplemental levels/(mg/kg)				P值 P-value
项目 Items	0 (对照 Control)	30	60	90	P值 P-value
空肠 Jejunum
淀粉酶 AMY/(U/g prot)	4 865.21±1 078.11^b	4 996.97±1 676.35^b	5 213.77±591.42^a	5 389.01±1 343.63^a	0.038
脂肪酶 LPS/(U/mg prot)	18.27±1.71^b	20.13±3.04^b	25.87±1.66^a	29.25±3.27^a	0.004
胰蛋白酶 Trypsin/(U/g prot)	19.47±1.54	19.97±2.65	21.86±0.76	22.56±1.74	0.201
回肠 Ileum
淀粉酶 AMY/(U/g prot)	4 024.75±1 535.65^b	4 245.34±1 433.78^b	4 727.65±723.75^a	4 926.23±1 065.38^a	0.036
脂肪酶 LPS/(U/mg prot)	17.50±1.31^b	17.94±1.39^b	18.29±0.43^b	25.47±2.82^a	0.030
胰蛋白酶 Trypsin/(U/g prot)	15.57±1.37^b	17.63±1.53^b	21.98±3.98^a	27.10±1.36^a	0.026

2.4 桑叶黄酮对肉兔营养物质表观消化率的影响

由表5可知,与对照组和30、60 mg/kg桑叶黄酮组相比,90 mg/kg桑叶黄酮组的干物质和粗纤维表观消化率显著提高(P<0.05);与对照组相比,30、60和90 mg/kg桑叶黄酮组的总能、粗蛋白和粗脂肪表观消化率显著提高(P<0.05);与对照组和30 mg/kg桑叶黄酮组相比,60、90 mg/kg桑叶黄酮组的酸性洗涤纤维表观消化率显著提高(P<0.05)。各组之间中性洗涤纤维表观消化率无显著差异(P>0.05)。

表5 桑叶黄酮对肉兔营养物质表观消化率的影响

Table 5 Effects of MLF on nutrient apparent digestibility of meat rabbits%

项目 Items	桑叶黄酮添加水平 MLF supplemental levels/(mg/kg)				P值 P-value
项目 Items	0 (对照 Control)	30	60	90	P值 P-value
干物质 DM	49.55±3.62^b	53.37±3.03^b	54.27±1.16^b	57.17±4.87^a	0.009
总能 GE	58.92±0.39^b	61.17±0.90^a	62.01±1.69^a	63.34±2.01^a	0.020
粗蛋白质 CP	70.08±0.92^b	73.34±1.72^a	76.05±4.15^a	77.72±2.23^a	0.012
粗纤维 CF	12.99±1.23^b	14.33±0.92^b	15.07±1.28^b	16.99±1.44^a	0.011
中性洗涤纤维 NDF	29.03±1.43	30.07±2.02	31.35±2.40	31.96±1.98	0.067
酸性洗涤纤维 ADF	19.46±1.02^b	21.07±0.65^b	23.04±0.68^a	24.63±0.98^a	0.021
粗脂肪 EE	76.36±0.82^b	79.15±0.93^a	80.77±0.66^a	81.86±1.02^a	0.031

2.5 桑叶黄酮对肉兔血清生化指标的影响

由表6可知,与对照组和30和60 mg/kg桑叶黄酮组相比,90 mg/kg桑叶黄酮组的血清葡萄糖和尿素氮含量显著降低(P<0.05)。各组之间血清碱性磷酸酶活性及总蛋白、白蛋白含量无显著差异(P>0.05)。

表6 桑叶黄酮对肉兔血清生化指标的影响

Table 6 Effects of MLF on serum biochemical indexes of meat rabbits

项目 Items	桑叶黄酮添加水平 MLF supplemental levels/(mg/kg)				P值 P-value
项目 Items	0 (对照 Control)	30	60	90	P值 P-value
葡萄糖 GLU/(mmol/L)	6.45±0.62^a	6.36±0.54^a	6.22±0.68^a	5.79±0.53^b	0.016
尿素氮 UN/(mmol/L)	5.87±1.03^a	5.77±1.40^a	5.33±0.74^a	4.94±0.34^b	0.029
碱性憐酸酶 ALP/(U/L)	102.44±29.23	109.35±35.27	112.71±33.56	126.08±36.54	0.375
总蛋白 TP/(g/L)	40.82±7.70	42.56±7.26	46.81±7.75	47.03±6.86	0.243
白蛋白 ALB/(g/L)	22.62±5.20	22.75±3.73	26.33±4.94	27.04±4.22	0.356

3 讨论

3.1 桑叶黄酮对肉兔生长性能的影响

黄酮类化合物是桑叶中重要的活性成分^[11]。席丽等^[12]在肉鸡上的研究发现,黄酮类化合物可有效改善肉鸡生长性能,增强营养物质的消化和吸收。雷春龙等^[13]研究表明,饲粮中添加桑叶黄酮可提升动物对营养物质的利用率,动物的生长性能和免疫功能也得到改善。本试验中,90 mg/kg桑叶黄酮组肉兔终末体重、平均日增重显著高于对照组,死亡率显著低于对照组和30、60 mg/kg MLF组;且30、60 mg/kg桑叶黄酮组的死亡率均显著低于对照组。各组腹泻频率随着饲粮中桑叶黄酮添加水平上升有下降趋势,90 mg/kg桑叶黄酮组虽然有腹泻但没有死亡现象。这表明饲粮中添加桑叶黄酮可有效降低死亡率,并提高肉兔的生长性能。

3.2 桑叶黄酮对肉兔十二指肠组织结构的影响

肠道是机体最大的消化器官,负责维持畜禽的健康,肠道内部是对机体摄入的营养物质进行消化和吸收的重要部位,研究表明动物肠道内的绒毛高度、隐窝深度及绒毛高度/隐窝深度是反映肠道营养物质消化吸收能力的标准^[14]。研究发现,饲粮中添加桑叶黄酮与鼠尾草酸复合物可以显著提高肉鸡回肠和空肠的绒毛高度和绒毛高度/隐窝深度,降低隐窝深度,表明桑叶黄酮与鼠尾草酸复合物可以促进肠道绒毛发育和消化液分泌,增加肠道面积,从而增加肠道对营养物质的消化吸收能力^[15]。另有研究表明,黄酮类化合物可以增加绒毛高度和降低隐窝深度,从而改善肠道形态^[16]。在本试验中,饲粮中添加桑叶黄酮显著提高了肉兔十二指肠绒毛高度和绒毛高度/隐窝深度,降低了隐窝深度,说明肠道消化吸收能力有所增强,表明桑叶黄酮可有效改善肉兔肠道内环境,促进小肠对营养物质的消化吸收,提高肉兔生长性能,同时使肠道防御能力增强,进一步强化肠道黏膜的免疫功能,这与腹泻率降低的结果相符。

3.3 桑叶黄酮对肉兔肠道消化酶活性的影响

机体通过体内各类消化酶作用分解食物中各种营养物质,从而对营养物质进行消化吸收,动物对营养物质的消化吸收与体内消化酶活性的高低联系紧密^[17]。研究表明,饲粮中添加桑叶粉可显著提高肉鸡肠道淀粉酶活性^[18],饲粮中添加桑叶黄酮可显著提高犊牛肠道淀粉酶活性和胃液中蛋白酶活性^[19]。在本试验中,饲粮中添加桑叶黄酮可提高肉兔空肠、回肠脂肪酶、淀粉酶和胰蛋白酶活性,促进肉兔对脂肪、干物质、蛋白质等营养物质的消化,最终达到提高生长性能的目的。

3.4 桑叶黄酮对肉兔营养物质表观消化率的影响

营养物质表观消化率是反映机体消化机能的重要指标,直观反映动物对各种营养物质的消化吸收水平。饲粮中添加桑叶黄酮可提高犊牛粗脂肪表观消化率,同时提高犊牛采食量和体重^[20]。饲粮中添加桑叶黄酮可提高断奶仔猪营养物质表观消化率,提高生长性能^[21]。本试验中,随着饲粮中桑叶黄酮添加水平的增加,粗蛋白质表观消化率提高,增加了肉兔体内蛋白质沉积,同时粗纤维、干物质、总能、酸性洗涤纤维和粗脂肪表观消化率提高,可能是因为桑叶黄酮提高了肉兔肠道消化酶活性,进而提高了机体对营养物质的消化吸收能力,这与生长性能结果中肉兔终末体重和平均日增重增加的结果一致。

3.5 桑叶黄酮对肉兔血清生化指标的影响

血清生化指标可以反映动物各组织器官功能和体内营养代谢情况,间接反映其生长性能。葡萄糖含量能够反映机体能量平衡及营养状况^[22]。本试验中各组肉兔血清葡萄糖含量均在正常范围内。尿素氮含量表达机体内氨基酸之间的平衡情况和蛋白质代谢功能。刘宽辉^[23]等研究表明,体内氨基酸达到平衡时,血清尿素氮含量会呈现下降趋势,尿素氮含量下降证明机体对蛋白质的利用率提升。机体对蛋白质的吸收代谢与总蛋白和白蛋白有关。有研究表明,饲粮中添加苦荞黄酮可显著提高仔猪血清白蛋白和总蛋白含量,促进机体对蛋白质的吸收^[24]。血清总蛋白含量间接反映了动物对蛋白质的吸收程度。本试验中,与对照组相比,试验组肉兔血清总蛋白和白蛋白含量有所升高,与生长性能提高的结果相符,说明饲粮中添加桑叶黄酮提高了蛋白质代谢水平,对营养物质的吸收起到了促进作用;血清尿素氮含量降低表明饲粮中添加桑叶黄酮促进了肉兔机体对氮的代谢,提高了蛋白质的合成代谢,抑制蛋白质的分解,促进蛋白质的沉积,进而提高了肉兔的生长性能。饲粮中添加桑叶黄酮通过提高肉兔肠道消化酶活性、提高营养物质表观消化率并改善肠道形态,增强机体对营养物质的代谢水平,从而提高肉兔生长性能。

4 结论

饲粮中添加桑叶黄酮能够提高肉兔生长性能,降低死亡率,改善肠道形态,提高肠道消化酶活性,提高营养物质表观消化率,降低血清葡萄糖、尿素氮含量。在本试验条件下,饲粮中添加90 mg/kg桑叶黄酮时效果最佳。

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